Furnace



Juli; 7, 1931.

w. A. GILCHRIST FURNACE "Original Filed April 19, 1920 2 have beengenerally unsuccessful" especia Patented July 7, 1931 I UNITED STAT SPATENT OFFICE WILLIAM a. emcnarsr, or cmcaeo, nam'uors I rumucaContinuation of applloatioii Serial 1%. sumo, am April 19, 1920. Thisapplication filed mm- 20,

' 1921. Serial No. 227,608. 1

This application is a continuation of an application for a patent onfurnaces, filed by me on April 19, 1920, bearing Serial No.

375,020. 5 The invention relates to furnaces adapted to. burn fuelshaving a large volatile content and is especially useful for bu thosecombustion chamber should have insufficient capacity to retain thevapors until they were substantially completely burned much of theirheat value would be lost by their premature escape from the combustionchamber.

This invention accordingly has as one of its objects the provision of afurnace adapted fuels whose percentage of moisture 1s very to vaporizethe volatile constituents of the great, vsuch as, bagasse, sawdust orlow grade coal. This furnace is designed to burn the volatilecombustibles in the vicinity of the solid fuel from which they arise andto use a portion of the heat derived from these buming gases to vaporizethe volatile portionsof the solid fuel. In furnaces heretofore'usedattempts have been made to drive off the volatile portions of the fuelby means of the heat derived from the burning of the solid particleswithin the fuel bed. These attemplts where a large quantity of moistureis present due to the absorption of heat directly from the adjacentburning solid particles by "the moisture without creatin a gas that iscapable of later being burne This invention aims to allow the volatilesincluding the vaporized moisture as well as the vaporized combustiblesto separate fromthe fuel bed and flow a short distance therefrom. Thesevapors are then heated to exceptionally high temperatures byaccumulating a large mass of them and burning them within refractorywalls which have been heated to incandescence; It is found thatincreases in temperatu're'of the vapors make possible their moreeflicient combustion so that larger proportions of them 've off theirheat as they burn. I'By keeping t ese burning gases somewhat'awa'y' fromthe solid moist fuel they do notbecomechilled by contact with therelatively'cooler'solid fuel and yet they are retained in'such aposition relative to v the bed offuel that a large amountof heat,

may be transferred directly from the burning gases to the fuel withoutloss of efliciency and the incandescent walls which retain and pocketthe vaporsuntil they are substantially completely burned are enabled toreflect and radiate heat emanating from the bur v gases onto the surfaceof the fuel. r If the .fuel principally by means of heat received fromthe combustible volatiles previously vaporized and burned somewhat apartfrom the solid fuel from which they issue.

Another'object of this invention is to provide a furnace capable ofburning solid fuels having a large volatile content which must bevaporized from the fuel in order to obtain eflicient combustion of thefuel.

vide a furnace for burning said fuels with a combustion chamber havingrefractory walls which will retain the hottest of the burning gases in aposition where they will transmit their high temperatures directly tothe solid fuels and also to the portions of the refractory walls whichwill reflect and radi-- ate a large amount of this heat back into thesame gases to further build up the temperatures of these hottest burninggases.

Other objects, advanta es and capabilities of this invention and inerent thereto will later become apparent.

The drawin selected for illustrating one embodiment ogthe'inventionshowsthe fuel disposed on an inclined grate but it should be understoodthat this invention is not limited to the use-of an'inclined grate butalso com- 95 prehends the disposition of the fuel in a furnace in othermanners. For instance, a bed of fuelhaving a greater thickness could besuccessfully employed. However, for describing the nature of theinvention the drawing discloses a furnace having a curved masonary wall12 facing the inclined grate 10 on which the bed of fuel is disposed.The wall 12, hereinafter sometimes referred to as the rear wall isinclined forwardly and is preferably curved as shown. The foot 13 of thewall is disposed rearwardly from the lower edge 14 or rear edge of thegrate sufficiently dersiood, however, that the flue need not be of thissame shape nor need it be located always in the position illustrated.However,

this location of the flue does aid in gathering.

the hottest of the burning gases into the upper forward part of thecombustion chamber where they cooperate with the walls to heighten theefliciency of I the furnace. Other means than the positioning of theflue may be employed to accomplish this desirable disposition of thehottest gases in this part of the chamber.

.It is found that the volatiles driven off by heat from the variousportions of such a bed of fuel have this characteristic. For instance,the higher portions of the fuel nearer the feed spout will give off morewater vapor and less combustible volatiles. than the drier fuel whichhas progressed further downward into the furnace. These unlike vaporshave a tendency to stratify or lane and do not mix as readily as couldbe desired. While the water vapors themselves cannot be burned yettheydo contain and carry along with them some Vaporswhich can be burned andif these water vapors were permittedto escape from the combustionchamber too quickly they would carry off with them much of the potentialheat units of the fuel. This invention therefore aims to break up anytendency toward laning, to cause a thorough mixture of all the vaporswhich arise from the fuel, and to heat the water vapors to a hightemperature and to cause them to give up any combustible volatiles whichthey may be carrying.

Accordingly, the refractory arch 16, which is preferably flat, extendsupwardly and rearwardly above the fuel from the front wall 17 of thefurnace to the front wall 18 of the flue 15.

For illustrating how the heat may be used which is obtained from thisfuel a boiler 19 illustrated and a horizontal flue 20 is shown extendingrearwardly under the boiler and connected with ihe outlet of the flue15.

While the invention is .not concerned with the particular describedconstruction of a grate yet a short description of the same will begiven to further explain the operation of this invention. The grate isprovided with tilting foraminous grate bars 21 each of which ispivotally supported. on its rear edge asat 22 and is provided with acrank arm 23 for tilting the same. Connected with alternate crank arms23 of the grate bars 21 are links 24: and 25, respectively, by means ofwhich the grate bars may be swung upwardly alternately to assist in therolling or tumbling movement of the fuel downwardly over the gratethereby bringing to the rearwardly exposed surface of the fuel bedportions of the fuel which has been less exposed to the action of theheat coming back from the combustion chamber.

In connection with this inclined type of grate there may be used alsothe stationary grate bars 26 and 27 which will retain the fuel withoutagitating it. The grate bars 27 should preferably passage of air.

A tilting floor plate 29 may be provided for the discharge of ash andthe fuel is fed onto the grate through the hopper 30. Rearwardly of thefloor plate 29 there is provided a floor 29'. a I

It is found to be advantageous to supply the air for combustion entirelyor almost entirely through the body of the solid fuel and this air isbrought into an air chamber 31 below the grate. When found desirablethis airchamber is divided by transverse partitions 32, 33, 34 and 35,each having a damper 36. The air enters the air chamber 31 from anintake flue 37 passing through the several partitions to the variousportions of the grate.

The employment of these partitions and dampers permits of the admissionof different quantities of air to the different portions of the fuelbed. In order to obtain higher temperatures than were heretoforepossible in burning fuel such as bagasse and to obtain therefor higherefficiencies it is necessary that the flame confining walls 16 and 12 aswell as the side walls of the combustion chamher, in short. be made ofhighly refractory material. These walls must absorb suflicient heat tocause them to become more or'less inhave openings 28 for the Ycandescent and they should also reflect heat as well as radiate it.Bricks absorbing high temperatures shfiuld, of course, be covered on theoutside by heat insulating material so that radiation losses from thecombustion chamber will be minimized and not militate against theefliciency of the furnace. Accordingly I have shown two courses ofbrick. the interior course 38 of which should be of excellent refractorymaterial and the outer course 39 should be composed of efficient heat'insulatin material. -These walls are then supporte on beams 40.

.vide rearwardly of the fuel ample space for the combustion required,yet it is constructed in such a manner that the hottest of the burn inggases will naturally gather forward of the rear portion of the chamberand thus somewhat closer to the fuel. The location of the hottest zonewill be underneath the exhaust outlet below the upper portions of therefractory arch of the rear refractory wall; This position of thehottest gases is close enough to the fuel so that a large amount of heatmay be transmitted directly from the gases to the fuel without, however,bringing the center of this mass of highest temperature gases nearenough to the said fuel to be chilled thereby. The relation of thishottest zone and the upper portions of the refractory walls which lieabove it is such'that a large amount of the heat transmitted by thegases to these incandescent walls will be reflected and radiateddirectly back into the zone from whence it came, thus helping to buildup the temperature of the gases tocause their more complete combustion.

,The inclination of the arch as it extends upwardly and rearwardly ofthe fuel gives rise to several new and important results. The upper partof the moist fuel bed gives off a large amount of steam whichwouldnormally rise to the arch, roll along it and es cape through theexhaust outlet if it were allowed to do so. The shape of the rear walland the arch is found to give the burning gases a rolling andreverberatory action causing them to sweep over the arch, wipe it clean$5 the fuel itself. Cooperating with the arch the of any stratifiedlayers of gases and mix these gases with the other gases in the chamber.The upper part of this arch," against which the extremely hot gasesimpinge, is found to become highly incandescent. In this condition thearch is excellently adapted to reflect, radiate heat into the chamberrearwardly of the fuel and also forwardly onto inclined rear wallconcentrates a large amount of radiated and reflected heat forwardlyonto "the fuel. The fuel is thus receiving its heat from outside of thefuel bed, the heat being produced by the volatilized combustibles ratherthan by the solid combustibles and yet the fuel does not have a harmfulchilling effect upon the gases which are burning rearwardly and aboveit.

Iclaim:

1. In a furnace for. burning bagasse and other fuels having a largemoisture content, a fuel support, a floor extendin rearwardly fromsubstantially the level of the rear of the support, said floor formingwith other flame confiningsurfaces an enlarged combustion chamber havingample space rearward of the fuel for retaining a large body of vaporizedfuel combustibles during a substantial portion of their combustion, saidchamber including a rear refractory wall arising from the floor andextending forwardly, and.

a refractory arch extending rearwardly and upwardly above the fuelsupport, the arch and rear wall being adapted to detain under theirupper portions the hottest of the burning gases and to reflect andradiate the heat received therefrom back into said hottest gases andalso onto the entire rearwardly exposed surface of the fuel and a fluein said chamber adapted to exhaust the burned gases between the rearedge of said arch and the front edge of said rear wall.

2. In a furnaceifor burning fuels of large moisture content, means for.supporting the fuel, an enlarged combustion chamber having flameconfining walls extending rearwardly of the fuel supporting means, anarch above the fuel inclined upwardly and rearwardly, a restrictedexhaust outlet in the highest portion of the chamber, and a rearrefractory wall extending upwardly and forwardly cooperating with thearch and flame confining walls to reflect and radiate heat onto therearward fuel surface, to detain the vapors therefrom rearwardly of thefuel, untilthe volatile combustibles are substantially burned, andcooperating with said arch to retain the gases of highest temperaturesunder the uppermost portions of the inclined surfaces of the arch andrear wall.

3. In a furnace, the combination of a rear-- Wardly and downwardlyinclined grate, a

' and upwardly inclined and adapted to reflect and radiate heat onto-allparts of the grate, and a flue leading from the combustion chamberbetween the arch and the wall said arch, said wall, said flue, and saidfloor, cooperating in said chamber to detain rearwardly of the fuelduring their combustion the combustible volatiles evaporated by the heatradiated from the arch and Wall and to-detain in the uppermost forwardportion of the chamber beneath tlieflue the hottest of these burninggases somewhat nearer the fuel and above it.

4. In a furnace, the combination of a rearwardly and downwardly inclinedgrate, a rearwardly and upwardly inclined refractory arch above thegrate, a refractory wall facing the grate and arch and constituting therear wall of a combustion chamber, a floor in said chamber extendingrearwardly from the rear edge of the grate, said wall extending fromapproximately the level of the rear end of the grate approximately tothe level of the rear-end of the arch, said wall having its lowerportion substantially upright and curving forwardly therefrom to itsupper end and being adapted to reflect and radiate heat onto all partsof the grate, and a flue leading from the combustion chamber between thearch and the wall.

5. In a furnace, the combination of a rearwardly and downwardly inclinedgrate, a rearwardly and upwardly inclined refractory arch abovethegrate, a refractory wallfacing the grate and arch and constituting therear wall of a combustion chamber, closed at the bottom against theadmission of air except through the grate, the wall extending fromapproximately the level of the rear end of the grate approximately tothe level of the rear end of the arch and being forwardly and upwardlyinclined and adapted to reflect and radiate heat onto all parts of thegrate, and a flue leading from the combustion chamber between the archand the wall.

6. In a furnace, the combination of a rearwardly and downwardly inclinedgrate, a refractory wall facing the grate and constituting the rear wallof a combustion chamber closed at the bottom against the admission ofair except through the grate, the wall extending from approximately thelevel of the rear end of the grate substantially above the level of theforward end of the grate and being forwardly and upwardly inclined andadapted to reflect and radiate heat onto all parts of the grate, andaflue leading from the upper part of the combustion chamber.

7. In a furnace, the combination of a rearwardly and downwardly inclinedgrate, a rearwardly and upwardly inclined refractory arch above thegrate, a refractory wall facing the grate and arch and constituting therear wall of a combustion chamber closed at the bottom against theadmission of air except through the grate, the wall extending fromapproximately the level of the rear end of the grate approximately tothe level of the rear end of the arch, the wall having its lower portionsubstantially upright and curving for.- wardly therefrom to its upperend and being adapted to reflect and radiate heat onto all parts of thegrate, and a flue leading from the combustion chamber between the archand the wall.

8'. In a furnace, the combination of a rearwardly and downwardlyinclined fuelsupport, a rearwardly and upwardly inclined refractory archabove the support'for reflecting and radiating heat downwardly on thesupport, a refractory wall facing the support and arch and constitutingthe rear wall of an enlarged combustion chamber, said chamber beingconstructed for and adequate for retaining a large body of thevolatilized combustibles during a substantial portion of theircombustion, a floor in said chamber extendport and a refractory archextending rearwardly upwardly from the upper end of said support,arefractory wall facing the support and constituting the rear wall of anenlarged combustion chamber, said chamber being constructed for andadequate .for retaining a large body of the volatilizedcombustiblesduring a substantial portion of their combustion, an imperforate floorin said chamber extending rearwardly from substantially the rear edge ofthe support, said wall extending from approximately the level of therear end of the support to substantially above the level of the forwardend of the support and being forwardly and upwardly inclined and adaptedto reflect and radiate heat onto the entire rearward surface of thesupport, and

a flue leading from the upper part of the combustion chamber.

10. In a furnace, the combination of a rearwardly and downwardlyinclined fuel support, a rearwardly and upwardly inclined refractoryarch above the support, a refractory wall facing the support and archand constituting the rear wall of an enlarged combustion chamber, saidchamber being constructed for and adequate for retaining a large body ofthe volatilized combust-ibles during a substantial portion of theircombustion, a floor in said chamber extending rearwardly from the rearedge of the support, said wall extending from approximately the level ofthe rear end of the sup-port approximately to the level of the rear endof the arch, the wall having its lower portion substantially upright andcurving for ardly therefrom to its upper end and being adapted toreflect and radiate heat onto the entire rear ward surface of thesupport, and a flue leading from the combustion chamber between the archand the wall.

11. In a furnace for burningfuels of large moisture content, means forsupporting the fuel, an enlarged combustion chamber exstitutin the rearwall of a combustion chamtending rearwardly from the fuel supportingmeans, said chamber including a rear refractory wall extending upwardlyto a level well above the top of said supporting means having a lowerportion thereof well rearwardl from the fuel supporting means to provi eample space for retaining the vola-,

tiles vaporized from the fuel until their combustible constituents aresubstantially burned,

said rear wall hav'i an upper portion exieuding forwardlyj n exhaustchamber said chamber being imperforate rearwarclly of the fuel sup ceptfor said flue, an arch mcline upwardly and rearwardly above the fuelsupporti means and coo rating with said rear w to pocket theurning-gases rearwardly of the fuel supporting means and to reflect andradiate heat from said gases onto the surface of the fuel supportingmeans. v

12. In a furnace, the combination of a rearwardly and downwardlyinclined grate, a refractory arch extendin rearwardly upwardly from theupper en of said grate, a refractory wall facing the grate adapted toreflect and radiate heat onto all parts of the grate curved upwardly andforwardly and extending from approximatel the level of the rear end ofthe grate to su stantially the level of the rear end of said-arch andconber, a cor in said chamber extending rearv a flue leadin wardly fromthe rear ed e of the grate, and

from the highest (fa-rt of the combustion c amber, said arch an wallbeing constructed to pocket in cooperation with the rest of thecombustion chamber the hottest burning gases under their refractorysurfaces adjacent the flue.

' In witness of the foregoing I aflix my signature.

WILLIAM A. GILCHRIST.

flue in the v rtin meansex-'

